Nanoscale machines

Electrochemistry is the basis of many important and modem applications and scientific developments such as nanoscale machining (fabrication of miniature devices with three dimensional control in the nanometer scale), electrochemistry at the atomic scale, scanning tunneling microscopy, transformation of energy in biological cells, selective electrodes for the determination of ions, and new kinds of electrochemical cells, batteries and fuel cells. 

The feasibility and limitations of molecular machines can hardly be emphasized any better than by Feynman s mixed message [1], namely that An internal combustion engine of molecular scale is impossible. Other chemical reactions, liberating energy when cold, can be used instead. Nanoscale machines, like their macroscopic counterparts, require power supplies of appropriate kinds and magnitudes for their functions. While macroscopic machines enjoy the simplicity of distinct active (ON) and inactive (OFF) states in the presence and absence of power supplies, respectively, molecular machines are in perpetual Brow-... 

As a model example of a nanoscale machine, we discuss here the physics of a single-molecular rotor capable of transforming surface thermal energy into random rotational fluctuations. A motor will result if this rotor is capable of permanently driving the motion of another rotor or the linear displacement of... 

The idea of constructing artificial molecular-level machines is recent. This topic was first discussed by R. P. Feynman, Nobel Laureate in Physics, in his famous address. "There is plenty of room at the bottom." to the American Physical Society in 1959. His idea was that of constructing nanoscale machines "atom by atom." a concept later expanded with fascinating perspectives but almost no practical progress, by K. E. Drexler. " With the advent of supramolecular chemistry."" it became... 

Fig.1 Schematic representation of effect of cutting edge radius in (a) conventional/macroscale machining and (b) micro/ nanoscale machining...

Ductile-mode micro-cutting is aimed at suppressing fracture in micro- or nanoscale machining of brittle materials like silicon wafers. Ductile-mode cutting can be achieved if the... 

In order to eventually be able to produce nanoscale machines and pumps, the swelling behaviour of the gel to be harnessed in order for mechanical work to be done. In order demonstrate the ability of the system to produce work, a modified version of the experimental set-up devised by Johnson-Kendall-Roberts (JKR experiment) (77) is used. 

The case of two rotating shafts in a molecular, nanoscale machine is quite the opposite. The shafts adhere spontaneously, leaping into contact, and provide... 

The use of light to power nanoscale machines is relevant for another important reason. If and when a nanotechnology-based indnstry will be developed, its products will have to be powered by renewable energy sources, because it has become clear that the problem of energy supply is a crucial one for human civilization for the years ahead. In this context, the constmction of nanomachines that harness solar energy, in the form of visible or near-UV light, is an important approach. 

For the first problem, we refer to the scale analysis of microscale and nanoscale machines. For the second problem, simulation and experimental results give... 

While the methods discussed represent appHed modalities that promise to be implemented within years, the scope of nanobiotechnology encompasses research which, though currently on the very frontiers of modern science, present innumerable possibihties for the future of nanomedicine. The prophesied abihty of nanoscale machines, or nanobots, to provide molecular level construction and repair to exterminate disease and erase genetic defects represents the pinnacle of nanomedicine aspirations. Although the inherent difficulties in the design and manufacture of such devices raise questions as to their feasibihty [153], research continues to explore nature s nanomachines and issues crucial to the development of nanobots. In cells, proteins are nanomachines that act as transporters, actuators, and motors, and are responsible for meticulous monitoring and repair processes [154,155],... 

The continuing development of such systems exhibits great potential in the areas of sensing, molecular switches, and nanoscale machines capable of doing work. Realization of these ambitious goals will likely require new synthetic methods to construct more complex hierarchical ion pair networks containing multiple aligned mechanically interlocked assemblies for amplified functionality and macroscopic device incorporation. 

The idea that atoms could be used to constmct nanoscale machines was first raised by Feynman There is plenty of room at the bottom [16, 17]. The key sentence of Feynman s talk was The principles of physics do not speak against the possibility of maneuvering things atom by atom . As we will see below, however, chemists do not believe in the possibility of realizing an atom-by-atom approach to nanostructures. 

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